<!DOCTYPE html>
<html>
<head>
    <title>web4</title>

</head>
<body>
<fieldset>
    <legend>跳转</legend>
    <span>你好中国</span><br><br>
    <from onchange="peal()">
        <table>
            <tr>
                <td>
                    <select id="website">
                        <option value="" selected></option>
                        <option name="website1" value="www.baidu.com">百度</option>
                        <option name="website2" value="www.163.com">网易</option>
                        <option name="website3" value="www.qq.com">腾讯</option>
                    </select>
                </td>
                <td>
                    <input type="text" name="websiteText" id="websiteText">
                </td>
                <td>
                    <button value="跳转" onclick="jump()">跳转</button>
                </td>
            </tr>
        </table>
    </from>

</fieldset>
</body>
<script type="text/javascript">
    var website;
    function peal(){
        website = document.getElementById("website").value;
        document.getElementById("websiteText").value= website;
    }
    function jump(){
        if(website==null){
            alert("请选择要跳转的网址");
        }else{
            window.open("http://"+website);
        }

    }

</script>
</html>
